Rockwell Automation 1757-FFLDC4 FOUNDATION Fieldbus System User Manual - Manual (Page 93)

Rockwell Automation Publication 1757-UM012A-EN-P - July 2011 93
Create an RSLogix 5000 Software Project Chapter 5
Schedule the ControlNet
Network This section is only for the 1757-FFLDC linking device that can be set up for
scheduling data transmissions on the ControlNet network.
To select a scheduled connection for communication to the Logix Block you
must run RSNetWorx for ControlNet software to schedule the network for the
connection to begin running.
On the Connection tab of the Module Properties dialog box, the ‘Use Scheduled
Connection over ControlNet’ box defaults with a checkmark. This parameter
works in conjunction with the RSNetWorx for ControlNet software to program
the 1757-FFLDC linking device for scheduling.
When using unscheduled connections, the ControlNet network needs to be
scheduled initially to set the network parameters (NUT, SMAX, and UMAX),
but not with the addition of each unscheduled Logix Block. Clear ‘Use
Scheduled Connection over ControlNet’ to select an unscheduled connection
for communication to the Logix Block.
There is time allotted in every network update time (NUT) for scheduled and
unscheduled communication. But, how your system is configured depends on
what information gets communicated.
A device’s critical information is guaranteed to be transmitted in the predefined
time interval (chunk) of the scheduled bandwidth. However, the unscheduled
time interval is shared by all of the nodes on the ControlNet network and
transmits messages and other non-critical information on a round-robin basis.
See the ControlNet Modules in Logix5000 Control Systems User Manual,
publication
CNET-UM001 , for more information.
IMPORTANT You must be offline in RSLogix 5000 software when creating your
RSNetWorx for ControlNet file for the Logix Blocks to display correctly
in RSNetWorx software.